The lack of soft high‐dielectric‐permittivity elastomers responsive to a low voltage has been a long‐standing obstacle for the industrialization of dielectric elastomer actuators (DEA) technology. Here, elastomers that not only possess a high dielectric permittivity of 18 and good elastic and insulating properties but are also processable in very thin films by conventional techniques are reported. Additionally, the elastic modulus can be easily tuned. A soft elastomer with a storage modulus of E = 350 kPa, a tanδ = 0.007 at 0.05 Hz, and a lateral actuation strain of 13% at 13 V µm−1 is prepared. A stable lateral actuation over 50 000 cycles at 10 Hz is demonstrated. A stiffer elastomer with an E = 790 kPa, a tanδ = 0.0018 at 0.05 Hz, a large out‐of‐plane actuation at 41 V µm−1, and breakdown fields of almost 100 V µm−1 is also developed. Such breakdown fields are the highest ever reported for a high‐permittivity elastomer. Additionally, actuators operable at a voltage as low as 200 V are also demonstrated. Because the materials used are cheap and easily available, and the chemical reactions leading to them allow upscaling, they have the potential to advance the DEA technology.

Polymers with high dielectric permittivity are promising for the construction of next-generation transducers and energy storage devices with improved energy density. Here, we report the synthesis, glass-transition temperature (T g ), and dielectric properties of polysiloxanes with different polarities. For this, we set out from poly(dimethyl-co-methylvinyl)siloxanes with different vinyl group content. The vinyl groups were then transformed into polar groups of various nature by an efficient one-step thiol−ene addition postpolymerization modification. We used the resulting collection of materials to establish structure− property relationships, side group design, and thermal and dielectric properties. Our results show that the T g increases with the polar group content and the strength of the polar group. A similar trend is observed for the dielectric permittivity as long as the T g of the polymer is well below 0 °C. Smaller polar groups tend to show a smaller increase in T g , and an increased linker length helps to decreases T g , which is generally favorable for high permittivity. Our findings guided us to design polysiloxanes with a permittivity as high as 27.7 and a T g of −18.2 °C. To the best of our knowledge, this is the highest dielectric permittivity of a polymer with a T g well below room temperature.

We report here the photophysical properties of a water-soluble conjugated polythiophene with cationic side-chains. When dissolved in aqueous buffer solution (PBS, phosphate buffered saline), there is ordering of the polymer chains due to the presence of the salts, in contrast to pure water, where a random-coil conformation is adopted at room temperature. The ordering leads to a pronounced colour change of the solution (the absorption maximum shifts from 400 nm to 525 nm). Combining resonance Raman spectroscopy with density functional theory computations, we show a significant backbone planarization in the ordered phase. Moreover, the ratio of ordered phase to random-coil phase in PBS solution, as well as the extent of intermolecular interactions in the ordered phase, can be tuned by varying the temperature. Femtosecond transient absorption spectroscopy reveals that the excited-state behaviour of the polyelectrolyte is strongly affected by the degree of ordering. While triplet state formation is favoured in the random-coil chains, the ordered chains show a weak yield of polarons, related to interchain interactions. The investigated polyelectrolyte has been previously used as a biological DNA sensor, based on optical transduction when the conformation of the polyelectrolyte changes during assembly with the biomolecule. Therefore, our results, by correlating the photophysical properties of the polyelectrolyte to backbone and intermolecular conformation in a biologically relevant buffer, provide a significant step forward in understanding the mechanism of the biological sensing.